This invention relates to a vanadium-phosphorus mixed-oxide oxidation catalyst which is particularly useful for maleic anhydride production.
The preparation of a mixed oxide comprising vanadium and phosphorus for use as a catalyst for a vapor-phase oxidation of a hydrocarbon feed is known in the art. In general, these oxidations suffer from a number of disadvantages, including relatively low yields of the desired product. For example, in the process of U.S. Pat. No. 3,293,268, a mixed-oxide catalyst of a vanadium-phosphorus composite is used to oxidize an n-butane feed to maleic anhydride. The oxidation temperatures employed are in the range 525.degree.-600.degree. C. and the yields are in the range 25-52 weight percent, based on the feed. The theoretical yield for the reaction EQU n-C.sub.4 H.sub.10 + 7/2 O.sub.2 .fwdarw. C.sub.4 H.sub.2 O.sub.3 + 4H.sub.2 O
is 169 weight percent. The actual yield reported in the above patent reference is less than 331/3% of theory.